New aircraft cabin systems are providing a larger number of video channels for passenger entertainment and information. It is desirable for each passenger to be able to select a movie or other video/audio entertainment program, while selecting his or her individual choice of program start time. This requires at least one independent audio channel for each passenger on the aircraft. As a result, it is preferable that there be 300 or more independent audio channels available on an aircraft for passenger entertainment and information.
Currently, video distribution systems utilized on aircraft provide passenger television connectivity using a frequency division multiplex scheme, very similar to the scheme used in cable television distribution systems. In this frequency division multiplex scheme, each video channel is carried on a different radio frequency (RF) carrier, with the multiple RF carriers typically ranging between the frequencies of 60 MHz and up to 400 MHz or higher. Distribution of the video channels to passengers is usually accomplished using coaxial cables which carry the frequency division multiplexed video signals. A video tuner at each passenger location can be used to select a particular RF carrier in order to view the information of a particular video signal modulated on that RF carrier.
It is desirable to provide an audio distribution system capable of providing 300 or more independent audio channels, but which is compatible with these existing aircraft video distribution systems. However, modulating this large of a number of audio signals on RF carriers in the same manner that video signals are modulated and carried by RF carrier signals would require excessive bandwidth. Consequently, an audio distribution system which is compatible with present aircraft video distribution systems, but which provides a large number of audio channels without requiring excessive bandwidth, would be a significant improvement in the art.